Grease



United States Patent M 3,117,086 GREASE Benfiamin A. Bolton, Gary, Ind, and Kenneth E. Kolb, Qorning, N.Y., assignors to Standard (Bil Company, Chicago, 111., a corporation of Indiana No Drawing. Griginal application Apr. 7, 1960, Ser. No. 20,550. Divided and this application June 9, 1961, Ser. No. 115,905

6 Claims. (Cl. 25233.6)

This invention relates to metal soaps of alkyl trimellitimide and particularly to greases incorporating said soap.

A new soap has been discovered which has the structure where R is an alkyl group containing from about 4 to about 30 carbon atoms, M is selected from the class consisting of alkali metals, alkaline earth metals, zinc and aluminum, and X is an integer from 1 to 3 corresponding to the valence of M. This soap former is hereinafter spoken of as an alkyl trirnellit-imide.

The imide is prepared by the reaction of trimellitic anhydride and a primary amine containing from 4 to about 30 carbon atoms under conditions such that the imide is formed. The free carboxyl group present in the imide is then reacted with an alkali metal, an alkaline earth metal, zinc or aluminum to produce the soap.

Illustrative of the primary amines which atford the alkyl group portion of the imide are: n-butylamine, tertbutylamine, Isoamylamine, n-hexylamine, n-octylamine, n-dodecylamine, n-tetradecylamine, cetylamine, n-octadecylamine, and triacontylamine. Amines containing from 6 to 20 carbon atoms are particularly suitable.

The metal soap contains an alkali metal such as lithium or sodium, an alkaline earth metal such as calcium or barium, zinc, or aluminum. Lithium, zinc, and barium are particularly good soap producing metals.

The soap of the invention is an excellent thickener for the hydrocarbon lubricating oils to produce grease type lubricants. The hydrocarbon oil portion of the grease may be any one of those now utilized in the manufacture of grease with conventional soaps and thickeners. While hydrocarbon lubricating oils having S.A.E. grade numbers from through 70 may be utilized, excellent greases are obtained by the use of the viscous hydrocarbon lubricating oils having an S.A.E. number of 40 and upwards.

An amount of the soap is introduced into the hydrocarbon lubricating oil to produce the desired amount of thickening; the particular amount needed is dependent upon the type of oil and the particular soap. In general, the grease will contain a major portion of the hydrocarbon lubricating oil and a relatively small amount of the soap.

These greases not only possess good appearance and 3,117,086 Patented Jan. 7, 1964 good lubricating qualities but also possess stability at higher temperatures.

Imide A mixture of 19.2 g. (0.1 mole) of trimellitic anhydride and 26.9 g. (0.1 mole equivalent) of C /C (/30) primary amine in 415 g. of Xylene was heated and refluxed for 2 hours. 1.8 ml. of Water (theoretical) was removed. Components are soluble in xylene at reflux. On cooling overnight a large ppt. formed which Was easily removed by filtering. Essentially yield was obtained. Product had an acid number of 122 compared to a theoretical of 127.

Soap

The soap of the imide can then be prepared by dissolving or emulsifying the imide in dilute lithium or sodium-hydroxide. The calcium soap may be prepared by adding CaCl to dispersions of the sodium or lithium soaps. Both the sodium and lithium soaps of octadecyl trimellit-imide are Water insoluble.

Grease In actual grease preparation it is desirable to prepare the soap in situ in the grease base oil. 45 g. of No. 40 base oil and 5 g. of mono octadecyl trimellitimide were stirred at F. The imide dispersed readily. An aqueous solution of lithium hydroxide was added and heating continued to 350 F. The soap was Well dispersed. Milling on a 3-roll mill gave a grease product. (The use of higher soap concentrations gives a higher consistency.) These greases were homogeneous, fairly opaque, and a light tan color. This application is a division of application Serial No. 20,530, tiled April 7, 1960.

Thus, having described the invention, what is claimed is:

1. A grease-type lubricant consisting essentially of a hydrocarbon lubricating oil and a thickening amount of a soap having the structure O X where R is an alkyl group containing from 4 to about 30 carbon atoms, M is a member selected from the class consisting of alkali metals, alkaline earth metals, zinc and aluminum, and X is an integer from 1 to 3 corresponding to the valence of M.

2. The grease of claim 1 wherein M is lithium.

3. The grease of Claim 1 wherein M is barium.

4. The grease of claim 1 wherein R is octadecyl.

5. The grease of claim 1 wherein R is octyl.

6. A grease consisting essentially of a major proportion of viscous hydrocarbon lubricating oil and a thickening amount of lithium octadecyl-trimellitimide.

References Cited in the file of this patent UNITED STATES PATENTS 2,330,239 Prutton Sept. 28, 1943 

1. A GREASE-TYPE LUBRICANT CONSISTING ESSENTIALLY OF A HYDROCARBON LUBRICATING OIL AND A THICKENING AMOUNT OF A SOAP HAVING THE STRUCTURE 